Therefore, these products with defined 5' and 3' ends accumulate exponentially with each round of DNA amplification -- that is, for every n cycles of PCR there will be 2 -fold amplification of the specific DNA fragment.
1 By themselves, PVCâs do not present any problem.  Bigeminy, Trigeminy, Quadrigeminy, etc. - ventricular bigeminy is the occurrence of a PVC every other beat, trigeminy is every third beat, quadrigeminy every fourth beat. The main point with these types is that the PVCâs are more frequent in these circumstances. They are otherwise little different from PVCâs.
Down syndrome (also called trisomy 21) is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome. Since it is cause by having a *third* set of certain genes, it is not dominant or recessive in the usual sense of the word.